Exemplo n.º 1
0
// encode serializes msg and prepends the message header. If msg is nil, it
// generates the message header of 0 message length.
func encode(c grpc.Codec, msg interface{}, cp grpc.Compressor, cbuf *bytes.Buffer) ([]byte, error) {
	var b []byte
	var length uint
	if msg != nil {
		var err error
		// TODO(zhaoq): optimize to reduce memory alloc and copying.
		b, err = c.Marshal(msg)
		if err != nil {
			return nil, err
		}
		if cp != nil {
			if err := cp.Do(cbuf, b); err != nil {
				return nil, err
			}
			b = cbuf.Bytes()
		}
		length = uint(len(b))
	}
	if length > math.MaxUint32 {
		return nil, Errorf(codes.InvalidArgument, "grpc: message too large (%d bytes)", length)
	}

	const (
		payloadLen = 1
		sizeLen    = 4
	)

	var buf = make([]byte, payloadLen+sizeLen+len(b))

	// Write payload format
	if cp == nil {
		buf[0] = byte(compressionNone)
	} else {
		buf[0] = byte(compressionMade)
	}
	// Write length of b into buf
	binary.BigEndian.PutUint32(buf[1:], uint32(length))
	// Copy encoded msg to buf
	copy(buf[5:], b)

	return buf, nil
}